/*
 * Copyright (c) 2014-2022 Monix Contributors.
 * See the project homepage at: https://monix.io
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package monix.execution.atomic.internal;

import sun.misc.Unsafe;
import java.lang.reflect.Field;

/**
 * INTERNAL API — used in the implementation of
 * `monix.execution.atomic.Atomic`.
 *
 * Being internal it can always change between minor versions,
 * providing no backwards compatibility guarantees and is only public
 * because Java does not provide the capability of marking classes as
 * "internal" to a package and all its sub-packages.
 */
final class NormalJava8BoxedObject implements BoxedObject {
    public volatile Object value;
    private static final long OFFSET;
    private static final Unsafe UNSAFE = (Unsafe) UnsafeAccess.getInstance();

    static {
        try {
            Field field = NormalJava8BoxedObject.class.getDeclaredField("value");
            OFFSET = UNSAFE.objectFieldOffset(field);
        } catch (Exception ex) {
            throw new RuntimeException(ex);
        }
    }

    NormalJava8BoxedObject(Object initialValue) {
        this.value = initialValue;
    }

    public Object volatileGet() {
        return value;
    }

    public void volatileSet(Object update) {
        value = update;
    }

    public void lazySet(Object update) {
        UNSAFE.putOrderedObject(this, OFFSET, update);
    }

    public boolean compareAndSet(Object current, Object update) {
        return UNSAFE.compareAndSwapObject(this, OFFSET, current, update);
    }

    public Object getAndSet(Object update) {
        return UNSAFE.getAndSetObject(this, OFFSET, update);
    }
}
